Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/70r18 vs 35/13.5r18 Tire Comparison Side By Side
  325/70-18 35/13.5-18 Difference
Diameter inches (mm) 35.91 (912.2) 35.01 (889.38) -0.9 (-22.82) -2.5%
Width inches (mm) 12.8 (325) 13.5 (343) 0.71 (18) 5.5%
Circum. inches (mm) 112.83 (2865.76) 110 (2794.07) -2.82 (-71.69) -2.5%
Sidewall Height inches (mm) 8.96 (227.5) 8.51 (216.09) -0.45 (-11.41) -5%
Revolutions per mile (km) 561.58 (348.95) 575.99 (357.9) 14.41 (8.95) 2.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.5 mph (31.38 km/h)
25 mph (40.23 km/h)24.37 mph (39.23 km/h)
30 mph (48.28 km/h)29.25 mph (47.07 km/h)
35 mph (56.33 km/h)34.12 mph (54.92 km/h)
40 mph (64.37 km/h)39 mph (62.76 km/h)
45 mph (72.42 km/h)43.87 mph (70.61 km/h)
50 mph (80.47 km/h)48.75 mph (78.45 km/h)
55 mph (88.51 km/h)53.62 mph (86.3 km/h)
60 mph (96.56 km/h)58.5 mph (94.15 km/h)
65 mph (104.61 km/h)63.37 mph (101.99 km/h)
70 mph (112.65 km/h)68.25 mph (109.84 km/h)
75 mph (120.7 km/h)73.12 mph (117.68 km/h)
80 mph (128.75 km/h)78 mph (125.53 km/h)
85 mph (136.79 km/h)82.87 mph (133.37 km/h)
90 mph (144.84 km/h)87.75 mph (141.22 km/h)
95 mph (152.89 km/h)92.62 mph (149.06 km/h)
100 mph (160.93 km/h)97.5 mph (156.91 km/h)

Gear Ratio / RPMs for New Tire (@ 65 mph)
2.35 2.73 2.94 3.07 3.21 3.31 3.42 3.55 3.73 3.91 4.11 4.27 4.56 4.88 5.13 5.29 5.38 5.71 6.17 7.17
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